Programmer/timers are routinely employed in appliances such as dishwashers, clothes dryers, microwave ovens and refrigerator ice makers. The programmer/timer triggers and times sequential events in an operational cycle according to a predetermined program.
Cam-operated programmer/timers typically incorporate a camstack. One familiar type of cam consists of a quasi-cylindrical drum having at least one cam profile. Each cam profile carries control information for one function of the associated appliance. To encode a cam profile, the radius of the quasi-cylindrical drum is varied around its circumference. A cam follower, in contact with the cam profile, is constrained to mechanically respond to the surface contour.
A camstack incorporates multiple cam profiles into a single drum. As the camstack rotates, each cam profile actuates one or more cam followers. Each cam follower can invoke a timed or programmed function by closing or opening an electrical contact. Devices are switched to activate integral functions performed by an appliance.
Certain appliance functions may require adjustment of event duration or event triggering in the appliance operational sequence. Since the programmer/timer is usually not easily disassembled, a remote adjustment method is required. Adjustment of an event may be required during initial setup, as the programmer/timer mechanism wears, or to account for consumer demands. Without an adjustment means, either the entire programmer/timer, as a unit, or the camstack, if accessible, would have to be replaced.
To surmount this limitation, some programmer/timers have historically incorporated an adjustment mechanism. A specific cam profile is mechanically linked to a manipulator external to the camstack enclosure. To permit adjustment, the cam profile is loosened from, or can be rotated by applying sufficient force about, the camstack's axis of rotation. Since the axis of rotation for the camstack remains static, adjacent cam profiles remain fixed. As a result, the functions controlled by the stationary cams are unaltered.
A disadvantage of this adjustment mechanism is that mechanical linkage to the cam profile cannot be disengaged. As the camstack rotates, the mechanical linkage and external manipulator are also compelled to move. Therefore, an additional mechanical load is placed on the power source that rotates the camstack.
For the foregoing reasons, an apparatus is needed that permits rotational adjustment of a cam profile in a camstack, but that can be disengaged from the camstack's drive system during periods when a rotational adjustment is not being made.
Thus, it is an object of the invention to provide an adjustment mechanism for a cam that is capable of altering the cam profile and that can be disengaged when not in use.
Further, it is an object of the invention to provide an adjustment mechanism for a camstack that is capable of altering a cam profile and that can be disengaged when not in use.
Further, it is an object of the invention to define a programmer/timer that incorporates the adjustable cam, that is mechanically simple, low cost and reliable.